Fuel dispensers in retail fueling environments include displays to provide information to the consumer, as well as to the station's operator, such as total amount of fuel dispensed and price-per-gallon for different grades of fuel. Background information and examples of fuel dispensers and retail fueling environments are provided in U.S. Pat. No. 6,453,204 (entitled “Fuel Dispensing System”), U.S. Pat. No. 5,956,259 (entitled “Intelligent Fueling”), U.S. Pat. No. 5,734,851 (entitled “Multimedia Video/Graphics in Fuel Dispensers”), U.S. Pat. No. 6,052,629 (entitled “Internet Capable Browser Dispenser Architecture”), U.S. Pat. No. 5,689,071 (entitled “Wide Range, High Accuracy Flow Meter”), and U.S. Pat. No. 6,935,191 (entitled “Fuel Dispenser Fuel Flow Meter Device, System and Method”), the entire disclosure of each of which is hereby incorporated by reference for all purposes as if set forth verbatim herein.
Regulatory requirements often mandate that fuel dispensers be separated from enclosed buildings by a predefined distance. The requirements also generally necessitate that the dispensers remain free from atmospheric confinement to allow any fuel vapors to disperse. As a result, fuel dispensers and their displays are typically freestanding and often located in a manner that exposes them to direct sunlight. For the same reasons, dispensers may additionally be exposed to environmental extremes, such as severe high and low temperatures. In certain scenarios, for example, the dispensers may be subject to an industry-accepted benchmark of extreme low temperatures of approximately negative forty degrees Fahrenheit (−40° F.).
Moreover, several requirements related to fueling transactions necessitate that certain information be conveyed to a consumer during the transaction. This information may include the cost per unit of volume, the total volume, and/or the total cost of the fuel being dispensed. This information is generally financial in nature and related to a sale that is in progress, completed, or has been interrupted. As such, the weights and measures authority for the relevant jurisdiction typically mandates that the information remain readable for a minimum specified amount of time. One reason for this is to preserve the information in order to complete the transaction manually without dispute in the event of a power failure.
Fuel dispensers use various display technologies to convey the information to consumers during the fueling transaction, examples of which include mechanical, electromechanical segmented vane (“vane”), incandescent segmented filament (“filament”), heated cathode vacuum florescent (“florescent”), cold cathode gas discharge (“cathode”), light emitting diode (“LED”), and liquid crystal. There are generally two types of liquid crystal displays (“LCDs”): reflective and transmissive. Use of each type of display technology, however, is not without drawbacks.
Mechanical and vane displays suffer in reliability due to the number of moving parts required. Additional precision is accompanied by additional mechanical complexity and increased costs. The display's rate of computation is limited by friction, inertial mass, and other constraints attendant with physically moving parts.
Filament, florescent, and cathode displays require significant electrical power. For the same reason, maintaining display information during power loss requires a disproportionally large battery, capacitor(s), or other power supply. Filament displays suffer progressive degradation modes including filament sagging, oxidation, and sputtering, as well as absolute failure modes. Florescent displays degrade in their light output intensity over time as both cathode emissivity and phosphor anode efficiencies degrade. Cathode displays degrade in their light output intensity over time by both electrode sputtering and cathode poisoning. As a result, the ability to use a display of these types is reduced or eliminated over time.
LED displays exhibit poor readability in sunlight and also require disproportionally large batteries to maintain display information during power loss. Due to their construction, LCDs attenuate total light throughput, which is worsened in the case of reflective-type LCDs due to the use of a reflector. Transmissive-type LCDs require a sufficient amount of rearward/backlighting in order to overcome direct sunlight exposure, as well as the above-mentioned attenuation, thereby increasing the electrical power required while reducing the useful life of the backlighting technology employed. As a result, the reliability of transmissive-type LCDs depends, at least in part, upon the source of the backlighting. A battery or other power source is required to maintain the backlighting during a power failure.
Fuel dispensers typically also include an input device to receive information from consumers, such as a keypad. The fuel dispenser's keypad and display may be replaced by a touchscreen which performs the functions of both the keypad and display. Depending on the technology used, incorporation of displays and touchscreens increases the initial cost of the dispenser, as well as maintenance and repair costs. Additionally, each type of display described above requires a constant source of energy in order to operate, thereby increasing each dispenser's operational costs. Also for this reason, they are unable to display or provide any information in the absence of power. This is aggravated in certain areas where the supply of electric power is inconsistent or unreliable. Additional devices, such as capacitors, generators, and battery backups, may be used to continuously provide power to the displays in the event of a power failure, but installation, use, and maintenance of these devices also increases costs.
Electrophoretic displays are informational displays that form visible images by rearranging charged pigment particles using an applied electric field. The electric field manipulates the electric charge exhibited by the particles so that the particles either migrate to the surface of the display or rest near the rear of the display. As a result, an image is created and presented on the display. The electrophoretic display continues to display the image even after the electric field is withdrawn until another electric field is applied to the display in order to rearrange the particles.
Physical transformations and behaviors occur in electrophoretic displays, however, when operating at low temperatures. For instance, the pigmented particles may undergo glassification even at temperatures that are above the industry-accepted minimum operating temperature of −40° F. The particles may be suspended in a dispersant, such as a hydrocarbon or siloxane, the dynamic viscosity of which is a function of temperature. As dynamic viscosity increases with decreasing temperature, the response time or “refresh rate” of the display becomes greater than the change in the information being displayed. Thus, the electrophoretic display is unable to present the information at the same speed that it is received.